1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same.
2. Description of the Related Art
High voltage devices require a low-density drift region in a drain so as to have breakdown characteristics against high voltages. The drift region occupies the largest area in the high voltage device. Larger drift region is required in a horizontal direction as the higher breakdown characteristic is required for the high voltage device.
Further, in order to realize a high voltage breakdown characteristic, it is necessary for the high voltage device to increase the length of a channel region for preventing the punch through between a source and a drain. The channel region occupies the second largest area in the high voltage device.
Hereinafter, a high voltage device according to the related art will be described in detail with reference to the attached drawings.
FIG. 1 is a cross-sectional view of a high voltage device according to the related art.
Referring to FIG. 1, a low-density drift region 11 is formed on a predetermined region of a p-type semiconductor substrate 10. A gate oxide layer 12 is formed on an upper surface of the p-type semiconductor substrate 10, and a field oxide layer 13 for a field plate is formed on the semiconductor substrate 10 corresponding to a part of the drift region 11.
A gate 14 is formed on the gate oxide layer 12 and the field plate 13. A source 15 and a drain 16, i.e., n-type doped region 15 having a high-density are formed adjacent to both sides of the gate 14 and in the semiconductor substrate 10. At this time, the source 15 is spaced apart from the drift region 11, and the drain 16 is formed in the drift region 11.
The channel region 17 is formed between the source 15 and the drift region 11 in the semiconductor substrate 10 below the gate 14, and electrons 18 flow from the source region 15 to the drain region 16.
In the conventional high voltage device as described above, the drift region 11 needs to be increased in its horizontal length due to its horizontal structure so as to improve the breakdown characteristic. This may act as limitations in high-integration and miniaturization of the semiconductor device.